Magnetic core



NOV. 25, 1930. w J MORRLL 1,783,050

MAGNETIC CORE Filed April 22, 1930 v Inventor: Wayne J. Mow-Pill,

I! is Att orn ey.

patented Nov. 25, 1930 UNITED STATES PATENT OFFICE WAYNE J. MORRILL, OIFORT WAYNE, INDIANA, .ASSIGNOR '10 GENERAL ELECTRIC COMPANY, ACORPQBATION OF NEW YORK mammgicoa Application filed April 22,

My invention relates to magnetic cores for electrical inductionapparatus such as transformers and reactors. Magnetic cores are oftenconstructed with air gaps in their magnetic circuits to produce theeifect of high reactance in their windings. The general object of theinvention is to produce an improved core of this type which can beeasily and quickly assembled and which will be mechanically strong andrigid.

The invention will be readily understood from the following descriptiontaken in connection with the accompanying drawing in which Fig. 1 showsa reactor having a laminated magnetic core constructed in accordancewith the invention. Fig. 2 shows a single layer or lamination of thecore shown in Fig. 1 and Figs. 3 and 1 are detail sectional views.

Like reference characters indicate similar parts in the differentfigures of the drawing.

The reactor shown in Fig. 1 includes a laminated magnetic core 10 havinga central winding leg 11 surrounded by a wind ing 12. The core has twooutside legs 13 and 14 connected by end yokes 15 and 16, the outside legand yoke sections of each lamination being integral and formed bypunching an opening in a single piece of magnetic sheet material. Theinner edge of each yoke section of each lamination is formed with anotch so that the inner face of each of the yokes 15 and 16 has asimilarly shaped notch. The ends of the winding leg 11 are shaped to fitthese notches but the winding leg is slightly shorter than. the distancebetween the notches so that there is a nonmagnetic air gap 17 in themagnetic circuit at one end at least of the winding leg.

The lamination sections forming the winding leg 11 are secured togetherby two rivets 18. A number of outer lamination sections are assembled toform a stack of the same thickness or height as that of the winding leg11 and, after placing the winding 12 on the winding leg 11, this windingleg is placed in position between the notches in the yokes 15 and 16,leaving a non-magnetic air gap between at least one end of the windingleg and the inner face of the adjacent 1930. Serial No. 446,376.

yoke. The winding leg 11 and the outer part of the core formed by theouter legs 13 and 14 and the yokes 15 and 16 are held tightly andrigidly together by a rivet 19. The end of the winding leg 11 next tothe rivet 19 and the inner face of the adjacent yoke at the base of itsnotch are formed with opposed recesses 20 and 21 respectively to fit therivet. The rivet 19 is of suitable nonmagnetic material such as brass orcopper so that it will not interfere with the effect of the air gap 17.

The size of the rivet 19 is such that it will pass readily through theair gap 17 and between the recesses 20 and 21 and without injury to thesurfaces of the rivet and recesses. Fig. 3 is a sectional detail viewthrough the axes of the rivets 18 and 19 and shows the rivet 19 in placeand before being tightened. The rivet 19 may have a head at one endbefore being placed in position in the air gap as shown in Fig. 3. Withthe rivet 19 in place, a head is formed on the other end, preferably bya hydraulic press. Besides forming the second headon the rivet 19, thispressure upsets or expands the rivet throughout its length, the rivetbeing of some suitable metal such as brass or copper which may be thusexpanded by the pressure. This expansion of the rivet 19 forces ittightly against every lamination on both sides of the air gap 17. Thisforces the opposite end of the winding leg toward the inner face of theyoke 16 and holds all the laminations of the winding leg and the outerportion of the core rigidly together without the necessity of any rivetsin the outer part of the core. The rigid support for every laminationnot only effectively prevents vibration and noise but also preventsdisplacement of the laminations and consequent variation of the air gapwhen the laminations are subjected to severe magnetic forces duringshort circuit or heavy load conditions in the winding.

The invention has been explained by describing and illustrating aparticular form of reactor constructed in accordance therewith but itwill be apparent that various changes and applications of the inventionma be made without departing from the spirit of 10 for securing thelaminations the invention or the scope of the appended claims.

What I claim as new and desire to secure by Letters Patent of the UnitedStates, is,- 5 1. A laminated magnetic core for electrical inductionapparatus, said core including a laminated outer part forming two outerlegs and yokes connecting said legs, a laminated central leg partbetween said gokes, means at least one of said parts together, therebeing a non-magnetic gap between at least one end of said windingleg'and the adjacent yoke, and a rivet through said gap, said rivetbeing expanded throughout its length against the adacent leg and yokelaminations.

2. A laminated manetic core for, electrical induction apparatus, saidcore including a laminated outer part forming two outer legs and yokesconnecting said legs, the leg and yoke portions of eac lamination beingintegral, a laminated central leg part between said yokes, means forsecuring the laminations of at least one of said parts together;

there being a, non-magnetic gap between at least one end of said windingleg and the I adjacent yoke, and a rivet through said gap,

said rivet bein expanded throughout its entire length against theadjacent leg and yoke laminations.

3. A laminated magnetic core for electrical induction apparatus, saidcore includin a laminated outer part forming two outer egs and yokesconnecting said legs, the inner faces of said yokes having notches, alaminated central leg part between said notches, means for securing thelaminations of at least one of said parts together, there bein anonmagnetic gap between at least one en of said winding leg and theadjacent yoke, and a rivet through said ap, said rivet being expandedthrou hout 1ts length against the adjacent leg an oke laminations.

In witness w ereof, I have hereunto set my hand this 19th day of April,1930.

WAYNE J. none.

